1. Field of the Invention
The present invention relates to novel 1-(3-substituted benzyl)-3-halogeno-4-(1-halogenoalky)-2-pyrrolidinone derivatives, to herbicides containing them and to processes for producing them.
2. Description of the Prior Art
It is disclosed that certain 2-pyrrolidinone derivatives have herbicidal activity in, for example, U.S. Pat. No. 4,110,105, U.S. Pat. No. 4,210,589 (division of U.S. Pat. No. 4,110,105), U.S. Pat. No. 4,069,038 (division of U.S. Pat. No. 4,119,636) or EP 134564A. Further, 3-chloro-4-chloromethyl-1-(3-trifluoromethylphenyl)-2-pyrrolidinone (common name, fluorochloridone), a typical compound disclosed in them, is already commercially available and has been put to practical use mainly for upland agriculture such as for winter wheat, cotton and sunflower. Further, physical properties and herbicidal test examples for two compounds, i.e., 1-benzyl-3-chloro-4-chloromethyl-2-pyrrolidinone and 1-(4-chlorobenzyl)-3-chloro-4-chloromethyl-2-pyrrolidinone are described in U.S. Pat. No. 4,110,105 and U.S. Pat. No. 4,210,589. In addition, U.S. Pat. No. 4,132,713 discloses a process for producing pyrrolidinone derivatives of the following general formula and states that such derivatives are useful as a herbicide: ##STR3## where X represents a hydrogen atom, chlorine atom or methyl group, Y represents a hydrogen atom, chlorine atom or bromine atom, Z represents a chlorine atom or bromine atom, R.sup.1 represents a hydrogen atom or an alkyl group with 1 to 4 carbon atoms, R.sup.2 represents an alkyl group with 1 to 6 carbon atoms, alkenyl group with 3 to 6 carbon atoms, a haloalkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, a cycloalkylalkyl group with 4 to 8 carbon atoms, benzyl group, chlorobenzyl group or represents the following formula: ##STR4## where R.sup.3 represents a hydrogen atom, alkyl group with 1 to 4 carbon atoms, acetyl group, chlorine atom, bromine atom, fluorine atom, iodine atom, trifluoromethyl group, nitro group, cyano group, alkoxy group with 1 to 4 carbon atoms, alkylthio group with 1 to 4 carbon atoms, alkylsulfinyl group with 1 to 4 carbon atoms, alkylsulfonyl group with 1 to 4 carbon atoms, trifluoromethylthio group, trifluoromethyl sulfinyl group, trifluoromethyl sulfonyl group, pentafluoropropione amide or 3-methyl ureido group and R.sup.4 represents a hydrogen atom, alkyl group with 1 to 4 carbon atoms, chlorine atom or trifluoromethyl group.
When the compounds disclosed in U.S. Pat. Nos. 4,110,105 and 4,210,589, as well as in the examples of U.S. Pat. No. 4,132,713 are used as the herbicide, a relatively large dose is required. In particular, their herbicidal effect against Echinochloa crusgalli which is one of the most important weeds in the paddy field is extremely insufficient both in pre-emergence and post emergence treatments and causes severe phytotoxicity to the rice plant which is a useful crop.